Electric machine and associated method

Abstract

A bearing assembly cooperates with a bearing seat formed in a bearing housing and includes a bearing having an inner ring, an outer ring and a rolling element in engagement with the rings and an anti-rotation device. The anti-rotation device engages the outer ring to the bearing housing limiting rotation of the outer ring within the bearing seat. The anti-rotation device includes a first feature engaging the outer ring and a second feature engaging the bearing housing. The features limit the rotation of the outer ring within the bearing seat. The first feature has an internal surface for engagement the outer ring and the second feature includes an engagement surface for engaging a protrusion extending from the bearing housing.

Description

BACKGROUND OF THE INVENTION[0001]The embodiments described herein relate generally to an electric machine, and more specifically, to a bearing assembly with a relative motion [bearing creep] impeding device associated with the electric machine.[0002]An electric machine is typically in the form of an electric generator or an electric motor. The machine typically has a centrally located shaft that rotates relative to the machine. Electrical energy applied to coils within the motor initiates this relative motion which transfers the power to the shaft and, alternatively, mechanical energy from the relative motion of the generator excites electrical energy into the coils. For expediency the machine will be described hereinafter as a motor. It should be appreciated that a motor may operate as a generator and vice versa.[0003]A stationary assembly, also referred to as a stator, includes a stator core and coils or windings positioned around portions of the stator core. It is these coils to ...

AI Technical Summary

Benefits of technology

The patent describes an anti-rotation device for use with a bearing in an electric machine. The device is designed to limit the rotation of the outer ring of the bearing within the bearing housing. It includes a first feature that engages the outer ring and a second feature that engages the bearing housing, which work together to prevent the outer ring from rotating. The first feature has an internal surface for engagement with the outer ring, while the second feature has an engagement surface for engagement with a protrusion extending from the bearing housing. This device helps to prevent damage to the bearing and ensures the proper functioning of the electric machine.

Problems solved by technology

This lapping may quickly greatly enlarge the housing bore, causing excessive noise and excessive movement between the motor stator and the motor rotor, resulting in rotor / stator strike.

The noise and strike may lead to early bearing and resultant motor failure.

These applications are plagued with bearing failures caused by the relative motion of the motor bearing outer ring in the motor housing, also known as bearing creep.

The upper unconstrained bearing, being closer to the fan, has a greater tendency for creep, but creep can occur in any bearing application, particularly those where accommodation is made for the bearing to move axially with respect to its housing.

However any solution that eliminates all relative motion has the disadvantage of not accommodating various phenomenon including temperature changes, dissimilar materials, and tolerance stacks that affect the relative axial position of the inner ring with respect to the outer ring.

Such a solution may result in excessive bearing preloads and reduced bearing life.

Further, interference fit between both bearing races is not recommended by bearing manufacturers.

Other methods, such as placing an o-ring, a polymer ring, an EC (expansion compensating bearing), between the bearing and the housing are either ineffective or not sufficiently durable.

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